Hi all,
I'm working on a standalone mp3 player for my car to be used with all
commercial car radios and directly with an audio amp too. It is not based on
a pc but on a microcontroller and uses a 20X4 characters LCD, a keypad, a FM
modulator with digital PLL system and accepts all size of CompactFlash
cards.
My idea is to able all people who have a generic car radio - cd or cassette
player without mp3 feature - to listen mp3 too without changing it. In other
words my system is in a 13cmX6cm teko soap box and it uses the already
installed car radio to amplify audio signal. What do you think about all
that ? Is there somebody interested ?

I was planning to make it an open source project such as the Yampp player.
I don't think there is on the market a unit with a FM transmitter integrated
that ables the user to listen mp3s on his car stereo.
Suggestions are well accepted.

Although I do think the linked device is exceptionaly clever, mainly because
it doesn't have (or need!) a display, it's small and portable, and it reads
MP3s off a USB thumbdrive which eliminates a whole range of transfer and
storage issues.

If you are referring to small transmitters as Itrip they are inexpensive but
they aren't good enough to provide a good sound because power transmitted is
very low to be compliant with FCC part 15.
However there is no such open source project.

Aha! Now, that is an interesting project. I think this is of most
interest to people (like me :() who have cars with proprietary-shaped
radios. People with normal bays would be better to buy a stereo with
line-in on the front, if they are already willing to do rewiring work.

With line in on the front? Haven't seen those inputs on new stereos
for years.

If you have a good design for the modulator I think it would be better
to start a project for developing just that, I don't see any point in
starting yet another MP3-player project. There are MP3 players
available off the shelf in all shapes, sizes and price ranges, most
people will chose their MP3 player based on very different criteria,
how well it works in a car is probably rather low on the list in most
cases. Since the commercially available FM-adapters are rather
expensive I think there would be some interest in a DIY project that
for a reasonable cost would extend the use of an existing MP3-player.

I have a year old JVC that has line-in on the front and plays MP3 discs.
Paid $150 and it works like a champ. Remembers the playback location when
you turn the key off (not all MP3 players do this even though they all do it
on redbook CDs), and randomizes across folders.

1) Do I have to unplug my existing FM antenna and plug in this device? This
means that I won't be able to receive any FM stations anymore.

2) Does it use a passive "T" configuration where both the signals from the
antenna and the signal from your modulator get mixed in to the same cable? A
passive mixer will cause your signal to transmit out through the antenna.

3) Does it use an active mixer where both the signals from the antenna and
from your modulator get amplified, buffered, filtered, and then mixed
together? If you can make a small device like this for less than the cost of
an iTrip then I'll buy one. I don't really need the MP3 player part of it
though, I already have one that I like, just give me the FM modulator/mixer
device as a standalone product. I would expect the audio quality to be at
least as good as the "Ramsey FM10" in order for this device to be worthwhile.

Those that have a cassette player can already do so, with a
run-off-the-mill mp3 stick and a 'tape adapter', i.e. a cassette dummy
that relays an audio signal directly to the tape head. People have
added CD playback to their car radios using that technique ever since
CD-walkmen exist.

Car radios new enough to have a CD-drive may just have a line-in on
their back, too.

Using an FM transmitter is almost certainly no option, because you
need a license to send on the public FM radio band.

--
Hans-Bernhard Broeker ( snipped-for-privacy@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.